Deepest Dive Under Antarctica Reveals Its Secrets

July 13, 2017

Tendrils of ice-covered brine, or brinicles, leak from sea ice near East Antarctica’s Dumont d’Urville Station. Ephemeral and seldom seen, they form when trapped, supercooled brine escapes from the ice and freezes less salty seawater.

Starting from the French scientific base on the Adélie Coast of East Antarctica, Laurent Ballesta and his team are ready to dive under the ice.

Sinking was done through a hole whose ice was about 10 meters thick.

“Grabbing the safety rope, I pull myself up inch by inch, but my shoulders get stuck. Suddenly I’m stunned by a sharp blow to the head: Cédric Gentil, one of my dive buddies, is trying to dig me out, and his shovel has struck my skull. Finally a hand grabs mine and hauls me into the air. Today’s dive is over—but it’s only one of 32.” Ballesta said.

Be astonished by the following photos

Emperor penguins head for the open ocean in search of food. The brownish patches above them are microalgae that cling to the sea ice and start to photosynthesize in spring. The photographer’s day camp was on one of these floes. Aptenodytes Forsteri (penguins)A hundred feet below the ice, a feather star waves its frondlike arms, groping for food particles. It’s an animal, not a plant—a cousin of sea stars—and it can swim. Photographer Laurent Ballesta dived as deep as 230 feet to get these shots. Promachocrinus KerguelensisA bioluminescent crown jellyfish, some 14 inches wide, floats by at 130 feet deep, glowing and trailing a dozen stinging tentacles. These bell-shaped plankton-eaters avoid direct light, which can kill them. Periphylla PeriphyllaA curious young Weddell seal, weeks old, comes in for a close-up. It may have been the pup’s first swim, says marine biologist Pierre Chevaldonné, who has worked at Dumont d’Urville. Weddell seals are the most southerly breeding mammal in the world.A diver watches an emperor penguin as it swims nearby. The brown patches above are microalgae, which cling to sea ice and photosynthesize in the spring.For nearly five hours at a time, divers documented plant and animal life up to 230 feet below the surface.One of Antarctica’s 16 species of octopus sits on the bottom. All Antarctic octopuses have a specialized pigment in their blood, turning it blue, to help them survive subfreezing temperatures.The most southerly breeding mammal in the world, a Weddell seal, swims beneath the ice. The seals stay near the coast, breathing air through holes in the ice.A diver swims more than 200 feet below the surface, where the light is dim and temperatures drop below 29 degrees Fahrenheit.A young Weddell seal sits in an ice gap. The juvenile will be about 10 feet long and weigh half a ton once its fully grown.The icy waters below Antarctica are also home to a variety of marine invertebrates.A seal swims beneath sea ice near East Antarctica’s Dumont d’Urville Station.A diver swims beneath several feet of Antarctic ice. The rope hanging nearby helps divers find their way back to the surface.Tethered to the seafloor more than 200 feet down, siphoning in water to collect food, orange sea squirts “look very simple, like sponges,” says Chevaldonné. “Yet they’re quite evolved”—they’re invertebrates, but the larvae have spinal cords. Synoicum Adareanum

A wary icefish takes cover in a kelp grove. These bottom dwellers have antifreeze proteins in their blood that help them withstand temperatures below 29°F. There are at least 50 species of icefish in the frigid waters of Antarctica. Family Nototheniidae (icefish); Himantothallus Grandifolius (kelp)Body stowed inside the ice floe, an anemone lets its tentacles dangle in the dark water. Marine biologist Marymegan Daly says it’s the only anemone species known to live in ice. Scientists can’t say how it penetrates the ice—or survives there. Edwardsiella AndrillaeAn octopus jets above a seabed packed with life. Antarctica has at least 16 species of octopuses. All have a specialized pigment in their blood called hemocyanin, which turns the blood blue and helps them survive subfreezing temperatures. Pareledone sp.

Original article was posted by Laurent Ballesta on National Geographic Magazine.

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